About Pipe Models

UIM supports three different pipe models. The models are defined by how a pipe provides other pipes and by the way the capacity is structured. Path analysis and other processes are designed to support these models.

Note:

Pipe models other than those described in this section are not supported by path analysis.

When you define Pipe specifications, you should keep these models in mind. For example, if you are defining a specification for a TDM facility, you must consider that it has a signal structure but does not have any child pipes.

The following pipe models are supported in UIM:

Cable/Pair Model: A parent pipe represents a copper or fiber cable that provides child pipes to represent twisted pairs or fiber strands. The cable pipe is configured in the following way:
- Minimum and maximum quantities for the child pipes are identical, so they are created automatically when the parent pipe is created in UIM.
- No capacity is required or provided.
- No signal structure is present.
Packet Facility Model: Supports Layer 2 links, such as ATM, Frame Relay and Ethernet. Facility pipes provide capacity in bulk to pipes that they enable. This capacity can be consumed completely by one pipe or in smaller quantities by multiple pipes. The facility pipe can enable any number of pipes if its maximum capacity and usage percentage are not exceeded.

Note:

The packet model is directly supported by Connectivity entities. Except in backward compatibility scenarios, you should use Connectivity entities to model packet connectivity.

Pipes based on the packet facility model are configured as follows:
- No signal structure is defined.
- The capacity required reflects the capacity that the pipe must be enabled by another pipe.
- The capacity provided is the total capacity provided by the facility.
- No child pipes are defined.
TDM Facility Model: Supports channelized technologies, such as TDM/PDH and SONET/SDH. Facility pipes provide channels that are used to enable service trails. A signal structure is associated with the facility pipe to define the pipe's capacity and channelization.

Note:

The TDM model is directly supported by Connectivity entities. Except in backward compatibility scenarios, you should use Connectivity entities to model TDM connectivity.

A TDM facility pipe is structured in the following way:
- The capacity required is the capacity that is required when enabled by another pipe.
- The pipe includes a signal structure that defines the pipe's capacity provided and how the signal is channelized. Channels are created either automatically or as needed in UIM depending on how the signal structure is organized.
- No child pipes are defined.

See UIM Concepts for more information about pipes.